Gastrointestinal Cancer

PD 05 - GI 2 - Poster Discussion

1041 - Lymphocyte Count Recovery After Chemoradiation Therapy Does Not Mitigate the Poor Prognosis of Esophageal Cancer Patients With Severe Radiation Induced Lymphopenia

Monday, October 22
11:15 AM - 11:21 AM
Location: Room 217 A/B

Lymphocyte Count Recovery After Chemoradiation Therapy Does Not Mitigate the Poor Prognosis of Esophageal Cancer Patients With Severe Radiation Induced Lymphopenia
W. Deng1, C. Xu Jr2, A. Y. Liu3, Z. Liao4, R. Mohan3, and S. H. Lin4; 1Department of Radiation Oncology, National Cancer Center/Cancer Hospital, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, China, 2Tianjin Medical University Cancer Hospital, Tianjin, China, 3The University of Texas MD Anderson Cancer Center, Houston, TX, 4Department of Radiation Oncology, The University of Texas MD Anderson Cancer Center, Houston, TX

Purpose/Objective(s): A number of studies have shown that radiation induced lymphopenia (RIL) during the course of radiation therapy is a poor prognostic factor in cancer patients. However, RIL occurs only temporarily during the course of therapy, and many patients do restore their lymphocyte count to near normal levels after treatment completion. How lymphocyte count recovery contributes to prognosis is unknown. We hypothesized that the degree of lymphocyte recovery after severe RIL could affect prognosis.

Materials/Methods: 756 patients with stage I-III thoracic esophageal or gastroesophageal junction carcinoma who received concurrent chemoradiation (CRT) with or without surgery from 2004-2015 were included. Complete blood count with lymphocyte before, during each week of CRT and first follow up after CRT (or before surgery) were collected. Lymphocyte nadir (Grades (G) 0-3 vs. G4) was defined as the lowest grade of lymphocyte count during CRT, lymphocyte recovery (G0-1 vs. G2-4) was the grade after CRT or before surgery. Both were classified according to CTCAE 4.0. Categorical clinical factors and lymphocyte grade were examined to predict survival using univariate and multivariate analysis according to cox proportional hazard regression model.

Results: With a median follow up time of 65.4 months, the 5 year overall survival (OS) for the entire group is 45.3%. G4 lymphopenia nadir during CRT was seen in 39% of patients. However, majority of patients recovered lymphocyte counts after CRT, with G0-1 lymphopenia after CRT in 54% of patients, although 46% of patients had persistent G2-4 lymphopenia. Patients with G4 lymphopenia nadir during CRT had significantly worse 5-year OS (35.4% vs 51.7%), DMFS (34.2% vs 46.2%) and disease specific survival (42.3% vs 59.1%) than G0-3 lymphopenia, which was an independent prognostic factor in multivariate analysis. However, the degree of lymphocyte recovery was not predictive of a better prognosis. When lymphocyte nadir and recovery were considered together, we found that no matter whether patients recovered from CRT or not, those who experienced G4 lymphopenia nadir during CRT had poorer OS. Even G4 nadir patients who had G0-1 recovery, their 5 year OS (36.6%) was still significantly worse than G0-3 nadir patients who did not recover from CRT (51.9%, p<0.01).

Conclusion: Despite the somewhat transient nature of lymphopenia during CRT, high grade lymphocyte nadir during CRT remained an independent predictor of long term poor clinical outcomes, regardless of the extent of lymphocyte recovery after CRT. This data implies that lymphocyte quality, rather than quantity, could have been affected by CRT, which may have long term disease control consequences.

Author Disclosure: W. Deng: None. C. Xu: None. A.Y. Liu: None. Z. Liao: Chair; ASTRO IES. R. Mohan: Research Grant; National Cancer Institute. Stock; General Electric. Member, International Advisory Committee; CERN. Member; Scientific Advisory Board. S.H. Lin: Research Grant; Genentech, Inc, Hitachi Chemical Diagnostic, Inc, Peregrine Pharmaceuticals. Speaker's Bureau; AstraZeneca, Inc.

Wei Deng, MD

National Cancer Center / Cancer Hospital, Chinese Academy of Medical Sciences

Disclosure:
No relationships to disclose.

Biography:
Wei Deng, M.D. is a postgraduate student at the Department of Radiation Oncology, National Cancer Center/Cancer Hospital, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, China. She is also currently a Research Medical Student at Department of Experimental Radiation Oncology, University of Texas MD Anderson Cancer Center. Her research interests include treatment strategies, risk prediction, and immune system functions during chemoradiation for esophageal carcinoma.

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